Exception on back button

[fedotxxl]

Reproducable in iOs 5.1.1 (Safari) and any default Android browser 4+. When browser loads data from back-forward cache (http://stackoverflow.com/questions/11979156/mobile-safari-back-button) an exception is thrown Uncaught TypeError: Cannot call method 'indexOf' of undefined http://abc.com/js/libs/backbone.queryparams.js:30 where line 30 is if (!fragment.indexOf(root)) fragment = fragment.substr(root.length);